SNOHOMISH — For some of us, it’s the one day of the year to like math.

With or without ice cream on top.

Today is National Pi Day, aka an excuse-to-eat-pie day.

Teachers serve up fun lessons on numbers. Eateries offer $3.14 deals on circular foods.

The pi symbol equals about 3.14 to infinity in math. Or about a one-eighth slice of a round pastry with fruit or crust with hot cheese.

Hence the March 14 — 3/14 — celebration that matches the first three digits of this famous mathematical constant.

Pi is used to represent the ratio of a circumference of a circle to its radius (whatever that means).

The answer, whether for a cherry pie, pepperoni pizza or a planet, is about 3.14, plus an infinite number of digits.

For starters: 3.1415926535897932384626433832795. The record for finding consecutive numbers, from 3.14 onward was 2.7 trillion digits at last count.

If it all sounds Greek to you, it should. The symbol for pi is actually a Greek letter, which looks like a lower case “n” in English text.

For Snohomish Pie Company, pi equals dollar signs.

“Pi Day has become the busiest holiday next to Thanksgiving,” said Shelby Beeman, manager of the cafes in Snohomish and Mountlake Terrace. “Every year it gets busier.”

The pie store gets a lot of Pi Day preorders, mainly for schools and corporations. Not to worry, on Pi Day each store will have 300 mini apple-berry crumb pies ($3.50) and 150 whole pies in many flavors ($22.99) with the pi symbol.

All are expected to sell.

Snohomish Pie Company also will host a popup Pi Day event with slices and minis at Narrative Coffee in Everett starting at 10 a.m. today and going until all crumbs are gone.

For schools, Pi Day is a perfect storm to teach the innards of math.

In Laura Calzadillas’ fifth-grade classroom, students draw pi pictures and listen to songs, some with piano keys set to the actual pi numbers.

“They get to see math through art and through music,” the Woodside Elementary teacher said. “Math is everywhere, not just in grocery stores and in class. It opens their eyes to a whole new world. Some say math is beautiful and I say, ‘Yes, it is.’”

To explain pi, she uses the book “Sir Circumference and the Dragon of Pi.”

At Horizon Elementary, the Imagine Children’s Museum is hosting an evening math party for students and families at the school, with games and pie.

It’s a big deal at universities.

Ten years ago, at 1:59 p.m., Stanwood High School senior Christy Swartz received her acceptance letter from Massachusetts Institute of Technology letting her know she had been accepted to the university renowned for its math and science. The month, day and time the e-mail was sent translate to 3.14159

Pizzerias and grocery stores have pie specials related to $3.14.

Burger joints also want a piece of the pi.

White Castle, which claims to be the founder of the modern hamburger, is offering a breakfast slider combo for $3.14. Gas from here for a road trip to the nearest White Castle in Las Vegas is under a $3.14 a gallon, if that’s any inspiration.

Pi Day also celebrates the birthday of Albert Einstein, who would have turned 140 on — now what are the odds of this — March 14.

So have a slice of pie for yourself and another for dear old Albert.

Andrea Brown: abrown@heraldnet.com; 425-339-3443. Twitter @reporterbrown.